Nucleated red blood cell and platelet counts in asphyxiated neonates sufficient to result in permanent neurologic impairment

Objective.?Recent research has suggested that a nucleated red blood cell (NRBC) count ≥26 per 100 white blood cells (%) or the development of a platelet count ≤100 000 per mm³ within five days of birth is characteristic of neonates who have experienced acute birth asphyxia.

Study design.?Study cases were from the population defined in a prior publication (Prenat Neonat Med 1997;2:286). The impaired neonates were separated into three groups: group 1, persistent non-reactive fetal heart rate (FHR) pattern from admission until delivery; group 2, reactive FHR pattern on admission followed by a tachycardia, non-reactivity, repetitive variable or late decelerations, and usually a loss of variability; group 3, cases with a reactive FHR pattern on admission followed by a sudden, rapid and sustained deterioration of the FHR usually in response to a hypoxic sentinel event that lasted until delivery or a bradycardia on admission. The FHR pattern in group 3 is considered most consistent with acute birth asphyxia. We then examined these FHR groups with respect to the presence of hematologic injury. Chi-square testing was used to describe differences among the study populations.

Results.?Of the original 52 cases, sufficient hematologic data were available for 47. Of these, the proportion of cases with NRBC ≥26% was: group 1, 10/21 (47.6%); group 2, 0/14 (0%); group 3, 0/12 (0%). Those with a platelet count ≤100 000 per mm³: group 1, 11/21 (52.4%); group 2, 2/14 (14.3%); group 3, 0/12 (0%). Group 1 was significantly more likely to have an NRBC count ≥26% than group 3 (p = 0.0135). A platelet count ≤100 000 per mm³ within five days of birth was also significantly more likely to be encountered in group 1 as compared with group 3 (p = 0.0072).

Conclusion.?In cases of acute birth asphyxia, hematologic injury was infrequently encountered. Our findings suggest that a neonatal NRBC count ≥26% and/or a platelet count ≤100 000 per mm³ within five days of birth is inconsistent with acute birth asphyxia.